In the weeks following the funeral, Sam needed crutches more and more. And it was now clear that there was something seriously wrong with his foot.

Kent: His foot’s now turning in, and his toes are curled up like he’d had a stroke.

Frantic now, his parents took him from doctor to doctor. A pediatrician, a podiatrist, and two orthopedic surgeons. Each said something different: It was Sam’s heel, his foot, his knee. Finally, they say, one of the orthopedic surgeons determined that it was all in Sam’s head—that he was still grieving over the loss of his grandmother.

Debbie: There was probably a shred of us that—that said, “Okay, maybe it is. Maybe our kid is crazy.” And that’s probably our biggest regret.

Now it was online searches, and phone calls to find treatment for Sam. In November 2007, they were referred to Cook Children’s Medical Center in Ft. Worth and a neurologist, Dr. Fernando Acosta Jr., who told them just what they wanted to hear.

Dr. Acosta: I said, Give me a chance. Let me try and see if I can straighten it out. I think I can.

Dr. Acosta wanted to inject botox into Sam’s leg. Another doctor had already tried this but it didn’t work. What’s more, it hurt... really hurt.

Kent: Sam laid on his stomach, and I literally had to lay on top of him to hold him down to keep his legs still ‘cause it burned. It hurt so bad as he’s screaming, at the top of his lungs.

But this time the pain paid off. Dr. Acosta straightened out Sam’s foot enough to fit into a brace. That and physical therapy at least had Sam off crutches and back on his feet. But it was still an ordeal, as Sam described in his video diary.

Sam's video diary: This is my brace. It’s very stiff and hard to walk around in. And it hurts a lot.

It was just a temporary fix. Dr. Acosta expected the disease to spread, and the shots would no longer help. His estimate was, within 5 to 10 years Sam’s entire body would be twisted. Sam would be in his 20s facing life in a wheelchair.

Dr. Acosta says he wanted to intervene as soon as possible to prevent that.

So in early 2008, he proposed a different and frightening treatment—one that might have Sam walking without a brace, and stop the progression of the disease.

The risks were frightening: infection, hemorrage, stroke. Doctors would be navigating around parts of the brain that control vision, movement and strength. There was little room for error.

And deep brain stimulation is a new treatment for dystonia. Doctors have been using it for less than 10 years, and only a handful of children have had it. Little is known about the long term effects on their brains. What’s more, the outcome is uncertain.

Dr. Acosta: There’s a possibility that we’ll do all this, and it may not work. And so, it’s a big leap of faith, I mean, to go through with this.

But once mom saw the pain Sam endured during his botox injections, she changed her mind.

Debbie: I said, “I can’t do this to him every 90 days. I just can’t do it.”

Debbie and Kent agreed that surgery was the way to go.

But the final decision would be Sam’s.

Dr. Acosta: In our hospital, at Sam’s age, it’s called "assent." Sam has to agree to the surgery or we can’t do it.

Sam: It took me a good, solid three weeks to finally warm up to the idea. And then another month to actually sign the papers.

Sam's video diary: Just 3 days ago, I signed off on it. I checked the little box and I said “give it to me.” And it wasn’t easy. It was probably one of the hardest things I ever had to do.

Kotb: What made you decide to have brain surgery?

Sam: Basically, it was, “All right, I can keep getting the most painful injections you’ll ever have in your life, every other month, and taking medicines I can barely keep down, no matter how much food I eat with ‘em, or I can get an eight hour surgery, be done with it.”

Kotb: Did you ever look at the risks?

Sam: I chose to ignore them.

Sams' video diary: So in two weeks’ time I will be administered the deep brain stimulation therapy. It will take a total of 8 hours and for 5 of those hours, I will be awake.

Deborah Ferguson, of KXAS TV in Dallas, Ft. Worth, followed Sam’s story for six months. She and her camera crew were there with him that day.

Dr. John Honeycutt was Sam's neurosurgeon.

Dr. Honeycutt, neurosurgeon: It’s a big operation. And it takes a long time to do it.

He would be implanting electrodes in Sam’s brain. The electrodes receive electrical pulses from pacemaker like devices implanted in Sam’s chest. If it works, this stimulation would stop the brain from sending those incorrect signals to his muscles, which caused them to contract.

Sam would be sedated, but conscious during the surgery, so doctors could see how he responded.

Dr. Honeycutt: It’s a difficult operation to go through being awake. And so doing it with kids, that adds a whole new level to it.

He began by literally screwing this headframe into Sam’s skull. That headframe gives doctors the coordinates of Sam’s brain.

Sam: I hated that thing. The worst part was when they were screwing it into my skull. You know, just a whole bunch of pain.

The target was the size of an almond. A team of 3 doctors—Dr. Honeycutt, Dr. Acosta, and neurology medical director Dr. Warren Marx, spent an hour plotting the path the electrodes would take to reach that target.

At 11 a.m., three hours into the procedure, word came that the surgery itself was about to begin.

Debbie: They called and told us “it’s time” and the walls closed in on us.

Dr. Honeycutt opened Sam’s scalp and began drilling two holes in his head.

Sam's video diary: When they’re cutting my head open, I will be awake. When they’re parting my skull, I will be awake. When they’re probing to find the right spots, I will be awake. When they insert the wires, awake.

Sam would feel little pain, because the brain has no nerve endings. But there’s still the stress of it all.

Dr. Honeycutt: The sound is the really the disturbing thing. And you can’t muffle it. You can’t put a silencer on the drill.

With the two holes drilled in Sam’s head, doctors made one final, remarkable check.

This thin needle has a tiny recording device at it’s tip. Doctors lowered it towards the target in Sam’s brain.

Dr. Acosta: Listening to the brain helps us confirm that we’re going to the right place that the targeting is correct.

After targeting was confirmed, doctors were ready to implant the electrodes. It was the moment of truth.

Debbie: We were in tears because it was something we never thought we would get to see them do again.

For younger brother Myles, it’s back to the good old days.

Myles: I love being able to hang out with my brother. I basically gotten my old brother back.

Not all is perfect with Sam.

Kent: He’s not a graceful runner right now, by any stretch. But I just love when he does run. It’s not for long periods of time.

But compared to what was, and what could have been, no one is troubled at all. And, his gait may still change, says Dr. Acosta.

Dr. Acosta: I think his brain is still getting used to it, so it’s possible that in another year, you wouldn’t notice anything. I want to make him perfect. But I don’t know.

Sam will have the stimulators in him for the rest of his life. That means no contact sports, and staying away from metal detectors. He’ll need new surgery about every five years, to change the batteries in the generators in his chest.

Kotb: So now when you picture his future, what do you see Sam at 20 or 30 or 40?

Debbie: That we gave him a level playing field. We gave him a chance. He’s not gonna have his disability. My hope and my prayer is it’s a forgotten thing for him.

Kotb: For some people surgery does defines them. "I had X," you know what I mean?

Sam: If you start a conversation with, “Hi, my name is bla lah lah, and I had this surgery at—on this date,” you have no life. And you need to find a new hobby, buddy.

Dateline wires the home of a volunteer, Jenny, from top to bottom with hidden cameras. Then she called repairmen to her house for a simple problem we created as a test with Jenny's pool. NBC's Chris Hansen reports.